ARTHUR WINSLOW — THE MISSOURI COAT, MEASURES. Ill 



here. It is exhibited, in brief, by tilted lower ( iarboniferous strata, in places under- 

 overlying horizontal Coal Measure beds, and also by easily recognized pre-Coal 

 Measure erosion. The latter is shown by the existence of Coal Measure rocks 

 deposited in these previously eroded valleys, and also by extensive accumulations 

 of the detritus of the lower Carboniferous rocks in such depressions; these phe- 

 nomena being frequently observable over the marginal area of the Coal Measures. 

 Just how extensive this Carboniferous elevation was cannot exactly he stated at 

 present. There is evidence that, in places, for some fifty miles in from the margin of 

 the Coal Measures the lower Carboniferous rocks were brought to the surface and 

 eroded, and it is probable that this extended much farther. It is possible that the 

 lower Carboniferous floor underlying the whole Coal Measure area of Missouri was 

 raised above water level and subjected to erosion. However this may be, we are 

 safe in stating that the Coal Measures were laid down upon an uneven surface, which, 

 at least over the marginal portion, was decidedly rough, broken by hills and ravines 

 as a result of erosion. The probable general condition is represented in the accom- 

 panying figure 26. 



^g^r^E^Sl 



Figure 20 — Ideal Section through the Ozark Uplift 

 Representing the probable condition of Hit- floor upon which the Coal Measures were laid down. 



Of still farther movement and renewed submergence before the Coal Measure 

 period, the presence of the Coal Measure rocks upon the uptilted lower Carbonifer- 

 ous strata, or in the channels eroded in the latter, yields ample proof. Just what 

 the extent of this submergence was and what were consequently the original limits 

 of the Coal Measures is another question. Of their original extension over the 

 Ozark area we have little or no evidence, other than the fact that the thickness of 

 the Coal Measures in the northwestern part of the state is very great, such that if 

 the upper rocks there once extended to the present eastern limits of that fi »rmatii >n. 

 they must have reached far beyond these limits and probably over the < )zark region. 

 That the upper Coal Measure rocks may never have extended to the present eastern 

 limits is, however, shown in the following pages ; therefore the former submergence 

 of the Ozarks is not necessary in order to explain the great thickness of the Coal 

 Measure strata. 



In support of the idea that the present marginal limits are near the original ones, 

 we have, on the other hand, the fact that tin' present marginal beds are distinctively 

 marginal deposits, and further, we have the negative evidence that no Coal Measure 

 strata, which maybe strictly classed as outliers, occur faraway from the general 

 margin of the formation, well within the Ozark area.* 



* In apparent negation of this statement, recent examinations, by the state geological survey, have 

 shown the presence of those peculiar deposits ol coal known as "coal pockets" in the \ ery heart of 



the Ozark region, in Douglas, Dent, Phelps, ami Crawford counties. These, 1 1 . >w .• \ . • c, bj i i< 



call for an original extension of the whole formation i" the extent of including them. It i- true 



that they are probably of Coal Measure age, bui On- i satisfactory theory of their formation is 



that they were accumulated in inland basins, or cavities, for I by previous erosion or solution of 



limestone, and were not connected with the main body of the Coal Mi isures. The I they 



are frequently found in and Burrounded by Lower Silurian rocks goes far toward proi ing thai the 

 later intervening rocks were either never deposited where such coal pockets are found or, if de- 

 posited, thai they were uplifted and entirely eroded before the deposition ol th< i H lire strata 

 began. 



